Atomic Structure Flashcards
C1.1 - C1.8. Pg 4-19
Properties of a proton
mass - 1
charge - 1+
located in the nucleus of the atom
properties of a neutron
mass - 1
charge - neutral
located in the nucleus of the atom
properties of an electron
mass - negligible
charge - 1-
located in the energy shells/levels of an atom
who had the first ideas about atoms
ancient Greeks
John Dalton model
John Dalton published his ideas about atoms in 1803. He thought that all matter was made of tiny particles called atoms which he imagined as tiny spheres that could not be divided.
J J Thompson model
100 years after Dalton, J J Thomson carried out experiments and discovered the electron. This led him to suggest the plum pudding model of the atom. In this model, the atom is a ball of positive charge with negative electrons embedded in it - like currants in a Christmas pudding.
Ernest Rutherford experiment
In 1909 Ernest Rutherford designed an experiment to test the plum pudding model. In the experiment, positively charged alpha particles were fired at thin gold foil. Most alpha particles went straight through the foil. But a few were scattered in different directions.
Ernest Rutherford model
The evidence he gathered in his experiment led Rutherford to suggest a new model for the atom, called the nuclear model. In this model, the mass of an atom is concentrated at its centre (the nucleus) and the nucleus is positively charged.
How many max electrons can be in the inner shell?
2
How many max electrons can be in the second shell
8
How many max electrons can be in the third shell?
8
What tells you how many electrons are in an atoms outer shell?
The group number
What tells you how many shells an atom has?
The period it’s in (on the periodic table)
How do you calculate relative atomic mass?
Ar = total mass of atoms/total number of atoms
or
Ar = (abundance × mass + abundance × mass)/total abundance
How do you calculate relative formula mass?
- work out how many atoms of each element there are in the chemical formula
- add together the Ar values for all the atoms of each element present
- so Mr=the Ar of all of the atoms in the formula
What is the relative formula mass of CO2?
It consists of one carbon atom (Ar = 12) and two oxygen atoms (Ar = 16):
Mr of CO2 = 12 + 16 + 16 = 44
It could also be calculated this way:
Mr of CO2 = (1 × 12) + (2 × 16) = 12 + 32 = 44
The is a 75% abundance of Cl with an atomic mass of 35 and a 25% abundance of Cl with an atomic mass of 37
Find Cl’s atomic mass
Relative atomic mass = [(75/100) x 35] + [(25/100) x 37] = 35.5
What is an isotope
Isotopes are atoms of the same element with different numbers of neutrons.They have the same number of protons.
What is the difference in properties between isotopes of the same element?
Isotopes of the same element have different physical properties (e.g. density, radioactivity) but the same chemical properties (e.g. reactivity)
